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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
The Pulsation Modes Of The Pre-White Dwarf Pg 1159-035, Jörge E.S. Costa, Matt A. Wood, Thomas J. Ahrens
The Pulsation Modes Of The Pre-White Dwarf Pg 1159-035, Jörge E.S. Costa, Matt A. Wood, Thomas J. Ahrens
Aerospace, Physics, and Space Science Faculty Publications
Context. PG 1159-035 , a pre-white dwarf with Teff ≃ 140 000 K, is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope (WET) showed a rich frequency spectrum allowing the identification of 122 pulsation modes. Analyzing the periods of pulsation, it is possible to measure the stellar mass, the rotational period and the inclination of the rotation axis, to estimate an upper limit for the magnetic field, and even to obtain information about the inner stratification of the star. …
Asteroseismology Of The Pg 1159 Star Pg 0122+200, Jianning Fu, Matt A. Wood
Asteroseismology Of The Pg 1159 Star Pg 0122+200, Jianning Fu, Matt A. Wood
Aerospace, Physics, and Space Science Faculty Publications
Context. The variable pre-white dwarf PG 1159 stars (GW Vir) are g-mode non-radial pulsators. Asteroseismology puts strong constraints on their global parameters and internal structure. PG 0122+200 defines the red edge of the instability strip and its evolutionary timescale is predicted to be dominated by neutrino emission. Its study offers the opportunity to better understand the instability mechanism and to validate the physics of the neutrino production in dense plasma. Aims. To achieve such a goal requires determining precisely its fundamental parameters. This is the goal of this paper. Methods. We present new multi-site photometric observations obtained in 2001 and …
Whole Earth Telescope Observations Of The Zz Ceti Star Hl Tau 76, Noël Dolez, Matt A. Wood, Thomas J. Ahrens, Nicole Silvestri
Whole Earth Telescope Observations Of The Zz Ceti Star Hl Tau 76, Noël Dolez, Matt A. Wood, Thomas J. Ahrens, Nicole Silvestri
Aerospace, Physics, and Space Science Faculty Publications
This paper analyses the Whole Earth Telescope observations of HL Tau 76, the first discovered pulsating DA white dwarf. The star was observed during two Whole Earth Telescope campaigns. It was a second priority target during the XCOV13 campaign in 1996 and the first priority one during the XCOV18 campaign in 1999. The 1999 campaign reached 66.5% duty cycle. With a total duration of 18 days, the frequency resolution achieved is 0.68 μHz. With such a frequency resolution, we were able to find as many as 78 significant frequencies in the power spectrum, of which 34 are independent frequencies after …
Observations Of The Pulsating White Dwarf G 185-32, Bárbara Garcia Castanheira, Matt A. Wood
Observations Of The Pulsating White Dwarf G 185-32, Bárbara Garcia Castanheira, Matt A. Wood
Aerospace, Physics, and Space Science Faculty Publications
We observed the pulsating hydrogen atmosphere white dwarf G 185-32 with the Whole Earth Telescope in 1992. We report on a weighted Fourier transform of the data detecting 18 periodicities in its light curve. Using the Hubble Space Telescope Faint Object Spectrograph time resolved spectroscopy, and the wavelength dependence of the relative amplitudes, we identify the spherical harmonic degree (ℓ) for 14 pulsation signals. We also compare the determinations of effective temperature and surface gravity using the excited modes and atmospheric methods, obtaining Teff = 11960 ± 80 K, log g = 8.02 ± 0.04 and M = 0.617 ± …
The Everchanging Pulsating White Dwarf Gd358, Souza Oliveira Kepler, Matt A. Wood, Nicole M. Silvestri, Thomas J. Ahrens
The Everchanging Pulsating White Dwarf Gd358, Souza Oliveira Kepler, Matt A. Wood, Nicole M. Silvestri, Thomas J. Ahrens
Aerospace, Physics, and Space Science Faculty Publications
We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired more than 232 000 independent measurements. We also report on 48 hours of time-series photometric observations in Aug 1996. We detected the non-radial g-modes consistent with degree ℓ = 1 and radial order 8 to 20 and their linear combinations up to 6th order. We also detect, for the first time, a high amplitude ℓ = 2 mode, with a period of 796 s. In the 2000 …
Asteroseismology Of A Star Cooled By Neutrino Emission: The Pulsating Pre-White Dwarf Pg 0122 + 200, Marlea Sean O'Brien, Matt A. Wood
Asteroseismology Of A Star Cooled By Neutrino Emission: The Pulsating Pre-White Dwarf Pg 0122 + 200, Marlea Sean O'Brien, Matt A. Wood
Aerospace, Physics, and Space Science Faculty Publications
Observation of g-rnode pulsations in the variable pre-white dwarf (GW Virginis) stars provides a unique means to probe their interiors and to study the late stages of stellar evolution. Multisite campaigns have in several cases proved highly successful in decoding pre-white dwarf light curves. Three previous attempts to untangle the pulsation spectrum of the coolest GW Virginis star, PG 0122+200, confirmed the existence of multiple g-modes but left the fundamental period spacing and therefore the star's mass and luminosity in doubt. We present an analysis based on new observations of PG 0122+200 obtained during a Whole Earth Telescope (WET) campaign …
Understanding The Cool Da White Dwarf Pulsator, G29-38, Scot J. Kleinman, Matt A. Wood
Understanding The Cool Da White Dwarf Pulsator, G29-38, Scot J. Kleinman, Matt A. Wood
Aerospace, Physics, and Space Science Faculty Publications
The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding post-main-sequence evolution, along with their cooling rates, which will allow us to calibrate their ages directly. The most important set of white dwarf variables to measure are the oldest of the pulsators, the cool DA variables (DAVs), which have not been explored previously through asteroseismology due to their complexity and instability. Through a time-series photometry data set spanning 10 yr, we explore the pulsation spectrum of the cool …